摘要:

Glycolipid (GL) was extracted from a heptoseless mutant ofSalmonella minnesotaby a mixture of phenol, chloroform, and petroleum ether. The GL was subjected to treatment with either acetic anhydride or phthalic anhydride; a portion of the GL was untreated. Both of the chemically treated preparations as well as the parent GL were examined for biological activity in the following systems: mouse lethality assays, rabbit pyrogenicity assays, and rabbit skin assays. The results of these studies indicated that both treated preparations were less toxic in mice than the parent GL. Compared with saline-treated controls, rabbits pretreated with either of the modified preparations exhibited a reduced pyrogenic response to a subsequent challenge dose of the homologous material but no reduction when challenged with the parent GL. Pretreatment with the unaltered GL rendered rabbits tolerant to the homologous material and, to some degree, to the modified preparations. Rabbits immunized with any of the three GL preparations exhibited dermal toxicity responses comparable with those in untreated animals. Based on these findings, it was concluded that treating GL with either phthalic anhydride or acetic anhydride results in a product which is less toxic in mice and less pyrogenic in rabbits than the parent GL, but which also exhibits a loss of ability to render rabbits tolerant to challenge with untreated GL.

ISSN:0008-4166    

DOI:10.1139/m75-195

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The sequence of appearance of cell wall degrading enzymes ofRhizoctonia solanipropagules was followed. Polygalacturonase (PG; EC 3.2.1.15) was induced earlier by sodium polypectate (NaPP) as compared with the induction of cellulase (Cx; EC 3.2.1.4) by carboxymethyl cellulose (CMC), cellobiose, or fibrous cellulose powder. Increasing CMC concentration to 0.5% shortened the time of Cx appearance. In Czapek medium containing citrus pectin, pectin lyase (PL; EC 4.2.2.10) was produced faster and at higher amounts than in a medium containing NaPP as the sole carbon source. PG appearance also preceded that of PL in media simultaneously supplemented with their respective inducers. NaPP, which induced production of PG, repressed Cx production. Among the Cx inducers, only CMC and cellobiose repressed PG production to any extent. At pH 6.0, either in a synthetic medium or on autoclaved bean hypocotyl segments, a delay in PG production as compared with Cx and PL production was observed. Optimal pH levels for enzyme production and activity were 4.0 and 5.0 for PG, 4.0 and 5.5 for Cx, and 8.0 and 7.5 for PL. PG was less repressed than Cx by glucose, cellobiose, and monogalacturonic acid, while PL was not affected.

ISSN:0008-4166    

DOI:10.1139/m75-196

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Scanning and transmission electron microscopy was applied for a morphological study of three strains ofBifidobacteriumgrown on solid or liquid media. The pronounced pleomorphism of the cultures previously observed by light microscopy was confirmed. A possible sequence of the morphological events during transformation from one to another pleomorphic form is proposed forB.bifidumandB.longum. Ultrastructural differences such as the formation of extensive mesosomal complexes inB.longumand characteristic plasmalemma particles only observed in theB.bifidummutant are described and discussed.

ISSN:0008-4166    

DOI:10.1139/m75-197

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Twenty-one substituted 1,4-naphthoquinones and five 8-quinolinols and copper(II) chelates were tested for antifungal activity againstCandida albicansandTrichophyton mentagrophytes. Compounds containing electron-releasing or weak electron-withdrawing groups in the 2 and 3 positions of the 1,4-naphthoquinone ring were the most active againstC.albicansat pH 7.0 in the presence of beef serum in the following order: 2-CH3O = 2,3-(CH3O)2 > 2-CH3 > 2-CH3S > 2-NH2 > 2,6-(CH3)2. ForT.mentagrophytesunder the same conditions the inhibitory 1,4-naphthoquinones contained the substituents 2-CH3O > 2,3-(CH3O)2 > 2-CH3S > 2-CH3 > 2-CH3(NaHSO3) > 2-NH2 > 2-C2H5S, 3-CH3 > 2,6-(CH3)2 > 2,3-Cl2 > 5,8-(OH)2.

ISSN:0008-4166    

DOI:10.1139/m75-198

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

A numerical analysis was carried out from a set of 165 telluric Gram-negative bacterial strains. The results allowed to join up 130 of them divided into eight phenons. Two of these phenons represent on their own 70% of the classified strains. The first of these phenons (52 strains) can be assimilated to the genusPseudomonasin the fluorescent group; the second one (41 strains) offers some analogies with theAcinetobacter. A representative strain type of the latter phenon was retained for later taxonomic comparisons.

ISSN:0008-4166    

DOI:10.1139/m75-199

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Navicula pavillardiHustedt, a marine, littoral, pennate diatom, can grow in the dark on glutamate or on the complex organic supplements tryptone or yeast extract. Growth on glutamate in the dark took place without an initial lag phase, whereas growth on tryptone began only after a 2-day lag phase that could be abolished by the simultaneous presence of glucose. Lactate inhibited growth in the dark on glutamate, but not photoautotrophic growth. Relatively low concentrations of glutamine inhibited photoautotrophic growth. The observed doubling time for heterotrophic growth on glutamate or tryptone was about 70 h, compared with a doubling time of 24 h under optimal photoautotrophic conditions. Glucose did not decrease the doubling time in the dark on tryptone. The assimilation efficiency for glutamate was 41%. The estimated necessary uptake rate for glutamate to account for the observed heterotrophic doubling time on glutamate was close to those measured with isotope techniques. The kinetic parameters for glutamate uptake, which followed Michelis–Menten kinetics, wereKs = 0.018 mM, andVmax = 7.0 × 10−10 μmol per cell per minute. Although several amino acids served as sole nitrogen sources for photoautotrophic growth and were demonstrated by the use of isotope techniques to enter the cells, they could not be used as substrates for growth in the dark. Glucose was not taken up to a significant extent except by cells grown in the presence of tryptone. Lactate was taken up only by dark-grown cells. Results of preliminary studies on the metabolic fate of several uniformly labeled amino acids are presented.

ISSN:0008-4166    

DOI:10.1139/m75-200

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

A total of three hundred and fifty-seven 2-year-old rainbow trout from a hatchery were examined for IPN virus over a period of 5 months. The overall virus isolation rate was 23.2%. The kidneys yielded virus most frequently while the spleen and pancreas-caeca yielded virus less frequently, and the gonads and feces yielded virus infrequently.During this period there was a decline in carrier rate as well as a decline in the numbers of infectious virions in the organs. These decreases were accompanied by elevated levels of neutralizing antibody in the sera. Fish with higher antibody levels were found to lose their IPN carrier status more frequently than those with lower antibody levels.

ISSN:0008-4166    

DOI:10.1139/m75-201

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The distribution, seasonal variation, origin, and significance of biological nitrogen fixation has been determined for a Chesapeake Bay estuary using the acetylene reduction technique. Studies over a 15-month period have shown that nitrogen fixation occurs predominantly in the surface intertidal (marsh) and subtidal sediments. Negligible activity was found in surface waters. A marked seasonal variation in nitrogen fixation was observed for intertidal sediments incubated at a standard 20 °C. Average rates of about 37 and 12 ng N/g dry sediment per hour were observed in the late fall months of 1972 and 1973, respectively, anddry sediment per hour during other seasons. Peaks of activity were lowered considerably when samples were incubated at ambient temperatures (in situ). Activity in the subtidal sediments was low (dry sediment per hour but showed a similar (~twofold) seasonal variation in nitrogen fixation potential. Light–dark and substrate addition experiments suggest that heterotrophic bacteria are the principal agents for nitrogen fixation in sediments. Integrated estimates of nitrogen fixation in the estuary indicate that biological fixation probably accounts for <5% of the total influx of nitrogen into the system. Rates of activity in the intertidal sediments are insufficient to account for the high productivity of marine angiosperms found in the marsh.

ISSN:0008-4166    

DOI:10.1139/m75-202

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Oxidative metabolism in whole cells ofEscherichia colistrain 82/r was inhibited byd-camphor when glucose, pyruvate, or succinate was used as substrate. Inhibition was not due to lower surface tension ind-camphor-treated cell suspensions nor was it a function of cell permeability. Succinic, lactic, and NADH-oxidase activities were inhibited in alumina powder cell-free extracts (80 μg of protein/ml) byd-camphor (1100 μg/ml). NADH: and succinic: DCPIP oxidoreductase enzymes were unaffected byd-camphor. Menadione (vitamin K3) restored succinic, lactic, and NADH-oxidase activities ind-camphor-inhibited cell-free extracts. Concentrations of menadione used to restore succinic and NADH oxidase activities were not stimulatory in non-camphor-treated extracts. Succinic oxidase activity ind-camphor-inhibited cell-free extracts was also restored by ubiquinone (Q6) but not by vitamin K1. These results are interpreted to indicate thatd-camphor may affect quinone function inE.coli.

ISSN:0008-4166    

DOI:10.1139/m75-203

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The physiochemical characteristics of the intracellular proteolytic enzymes ofOidiodendron kalrai, a neuropathogenic fungus, were studied. The organism in the yeast phase was grown in a semisynthetic medium containing 1% tryptone, at 37 °C for 48 h, on a gyrotory shaker. The crude extract was prepared by breaking the cells in a French pressure cell and the proteolytic activity was tested against biological substrates. The cell-free extract hydrolyzed casein, hemoglobin, lactalbumin, gelatin, elastin, collagen, and purified rabbit renal basement membrane to various degrees. Optimal proteolytic activity was observed at pH 6 and at 32 °C. Calcium and EDTA did not affect the enzymatic activity; however, activity was partially inhibited by sulfhydryl-blocking agents and by heat-inactivated horse, calf, and human serum. The extract was totally inactivated by exposure to a temperature of 70 °C for 60 min. Storage at −76 °C or −15 °C for 6 months or at 4 °C for 4 weeks did not affect protease activity.

ISSN:0008-4166    

DOI:10.1139/m75-204

出版商:NRC Research Press    

年代:1975

数据来源: NRC